From: Luis Machado <luis.machado@arm.com>
To: Simon Marchi <simark@simark.ca>,
Andrew Burgess <aburgess@redhat.com>,
Thiago Jung Bauermann via Gdb-patches
<gdb-patches@sourceware.org>
Cc: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Subject: Re: [PATCH v3 6/8] gdb/remote: Parse tdesc field in stop reply and threads list XML
Date: Fri, 3 Feb 2023 11:27:54 +0000 [thread overview]
Message-ID: <d7f2643e-f381-0315-0030-50dedcd8d592@arm.com> (raw)
In-Reply-To: <d0640114-a164-dffb-4901-0bd0df0ed14f@simark.ca>
On 2/1/23 20:16, Simon Marchi via Gdb-patches wrote:
>> IIUC, the tdescs would be deleted during the
>> pop_all_targets_at_and_above, when the refcount of the remote_target
>> gets to 0 and it gets deleted. And the threads would be removed in
>> generic_mourn_inferior just after.
>>
>> An idea could be to call generic_mourn_inferior before
>> remote_unpush_target (no idea if it works). Another one would be to
>> get a temporary reference to the remote_target object in
>> remote_unpush_target, just so that it outlives the threads.
>> Or maybe we should say that it's a process target's responsibility to
>> delete any thread it "owns" before getting deleted itself.
>
> Another question related to this popped while reading the following
> patch. When creating a gdbarch from a tdesc, the gdbarch keeps a
> pointer to that tdesc (accessible through gdbarch_target_desc). And
> AFAIK, we never delete gdbarches. So I suppose the gdbarch will refer a
> stale target desc. At first I thought it wouldn't be a problem in
> practice, because while that gdbarch object still exists, nothing
> references it (it is effectively leaked). But then I remember that we
> cache gdbarches to avoid creating arches with duplicate features. So
> later (let's say if you connect again to a remote), we might want to
> create a gdbarch with the same features as before, and we'll dig up the
> old gdbarch, that points to the now deleted tdesc.
The target descriptions for aarch64 are all cached using a map in gdb/aarch64-tdep.c:
/* All possible aarch64 target descriptors. */
static std::unordered_map <aarch64_features, target_desc *> tdesc_aarch64_map;
I don't think we should try to delete those, and they should live throughout the life of gdb (unless things get large, then we might consider cleanups).
>
> Perhaps it's possible to generate a crash with the current
> implementation by connecting, disconnecting, connecting again, and then
> doing something that uses the thread-specific gdbarch.
>
> Simon
>
next prev parent reply other threads:[~2023-02-03 11:28 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-30 4:45 [PATCH v3 0/8] gdbserver improvements for AArch64 SVE support Thiago Jung Bauermann
2023-01-30 4:45 ` [PATCH v3 1/8] gdbserver: Add assert in find_register_by_number Thiago Jung Bauermann
2023-01-31 17:05 ` Simon Marchi
2023-01-31 19:49 ` Thiago Jung Bauermann
2023-02-01 15:43 ` Simon Marchi
2023-01-30 4:45 ` [PATCH v3 2/8] gdbserver: Add PID parameter to linux_get_auxv and linux_get_hwcap Thiago Jung Bauermann
2023-02-01 9:07 ` Luis Machado
2023-02-01 10:54 ` Andrew Burgess
2023-02-01 16:01 ` Simon Marchi
2023-02-01 19:33 ` Thiago Jung Bauermann
2023-02-01 19:53 ` Simon Marchi
2023-02-01 21:55 ` Thiago Jung Bauermann
2023-02-06 19:54 ` Pedro Alves
2023-02-06 20:16 ` Simon Marchi
2023-02-07 15:19 ` Pedro Alves
2023-02-07 21:47 ` Thiago Jung Bauermann
2023-02-09 1:31 ` Simon Marchi
2023-02-10 3:54 ` Thiago Jung Bauermann
2023-02-07 22:28 ` Thiago Jung Bauermann
2023-01-30 4:45 ` [PATCH v3 3/8] gdbserver/linux-aarch64: Factor out function to get aarch64_features Thiago Jung Bauermann
2023-02-01 8:59 ` Luis Machado
2023-02-01 16:04 ` Simon Marchi
2023-02-01 22:13 ` Thiago Jung Bauermann
2023-01-30 4:45 ` [PATCH v3 4/8] gdbserver/linux-aarch64: When thread stops, update its target description Thiago Jung Bauermann
2023-02-01 9:05 ` Luis Machado
2023-02-01 11:06 ` Andrew Burgess
2023-02-01 16:21 ` Simon Marchi
2023-02-01 16:32 ` Luis Machado
2023-02-02 2:54 ` Thiago Jung Bauermann
2023-02-02 3:47 ` Simon Marchi
2023-02-03 3:47 ` Thiago Jung Bauermann
2023-02-03 11:13 ` Luis Machado
2023-02-04 15:26 ` Thiago Jung Bauermann
2023-02-03 11:11 ` Luis Machado
2023-02-04 15:21 ` Thiago Jung Bauermann
2023-02-06 9:07 ` Luis Machado
2023-02-06 12:15 ` Thiago Jung Bauermann
2023-02-06 20:29 ` Pedro Alves
2023-02-07 8:11 ` Luis Machado
2023-02-07 14:39 ` Thiago Jung Bauermann
2023-02-03 10:57 ` Luis Machado
2023-02-04 6:18 ` Thiago Jung Bauermann
2023-02-06 20:26 ` Pedro Alves
2023-02-07 21:06 ` Thiago Jung Bauermann
2023-02-09 2:46 ` Simon Marchi
2023-02-10 3:29 ` Thiago Jung Bauermann
2023-02-10 14:56 ` Luis Machado
2023-02-10 15:04 ` Tom Tromey
2023-02-10 15:28 ` Luis Machado
2023-02-10 17:26 ` Thiago Jung Bauermann
2023-02-10 21:01 ` Simon Marchi
2023-01-30 4:45 ` [PATCH v3 5/8] gdbserver: Transmit target description ID in thread list and stop reply Thiago Jung Bauermann
2023-01-30 12:52 ` Eli Zaretskii
2023-01-30 14:05 ` Thiago Jung Bauermann
2023-02-01 9:39 ` Luis Machado
2023-02-01 12:07 ` Andrew Burgess
2023-02-01 13:03 ` Eli Zaretskii
2023-02-01 17:37 ` Simon Marchi
2023-02-02 20:36 ` Thiago Jung Bauermann
2023-02-02 20:56 ` Simon Marchi
2023-02-01 20:46 ` Simon Marchi
2023-02-02 21:43 ` Thiago Jung Bauermann
2023-02-01 14:51 ` Andrew Burgess
2023-02-01 17:03 ` Simon Marchi
2023-02-02 19:52 ` Thiago Jung Bauermann
2023-02-02 20:51 ` Simon Marchi
2023-02-03 2:44 ` Thiago Jung Bauermann
2023-02-03 16:29 ` Andrew Burgess
2023-02-04 6:08 ` Thiago Jung Bauermann
2023-02-03 11:22 ` Luis Machado
2023-02-03 12:50 ` Simon Marchi
2023-01-30 4:45 ` [PATCH v3 6/8] gdb/remote: Parse tdesc field in stop reply and threads list XML Thiago Jung Bauermann
2023-02-01 9:52 ` Luis Machado
2023-02-05 0:06 ` Thiago Jung Bauermann
2023-02-06 9:10 ` Luis Machado
2023-02-01 14:32 ` Andrew Burgess
2023-02-01 19:50 ` Simon Marchi
2023-02-01 20:16 ` Simon Marchi
2023-02-03 11:27 ` Luis Machado [this message]
2023-02-03 13:19 ` Simon Marchi
2023-02-03 16:33 ` Andrew Burgess
2023-01-30 4:45 ` [PATCH v3 7/8] gdb/aarch64: Detect vector length changes when debugging remotely Thiago Jung Bauermann
2023-02-01 9:58 ` Luis Machado
2023-02-01 15:26 ` Andrew Burgess
2023-02-01 20:20 ` Simon Marchi
2023-02-03 11:31 ` Luis Machado
2023-02-03 16:38 ` Andrew Burgess
2023-02-03 19:07 ` Simon Marchi
2023-01-30 4:45 ` [PATCH v3 8/8] gdb/testsuite: Add test to exercise multi-threaded AArch64 SVE inferiors Thiago Jung Bauermann
2023-02-01 10:10 ` Luis Machado
2023-02-06 19:11 ` [PATCH v3 0/8] gdbserver improvements for AArch64 SVE support Pedro Alves
2023-02-06 20:05 ` Simon Marchi
2023-02-06 21:06 ` Pedro Alves
2023-02-07 13:49 ` Simon Marchi
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